This invention relates to a conveyor roller assembly mounted on a curved section of a conveyor frame and wherein each conveyor roller has a tapered outer surface, for example, of the general type disclosed in U.S. Pat. No. 5,988,362. Such a conveyor roller assembly is used to move packages around a curved section of a conveyor frame. Commonly, each conveyor roller includes a tapered steel tube having a tapered outer surface extending the full length of the tube. Such a tapered tube is expensive to produce and requires different bearing assemblies for supporting opposite ends of each tapered tube so that the tube is free to rotate. In addition, substantial time is required to install and/or replace a conventional tapered roller conveyor tube within the curved frame sections.
The present invention is directed to a conveyor roller assembly for use in a curved section of a conveyor frame and which substantially reduces the cost of manufacturing the roller assembly as well as substantially reduces the weight of the assembly. The weight reduction is highly desirable in that it reduces shipping and handling costs and efforts. In addition, the conveyor roller assembly of the invention reduces the operating noise level of a curved section of a conveyor and extends the service life of a curved conveyor section. The conveyor roller assembly of the invention further eliminates the need for a package distribution center from maintaining an inventory of expensive conventional tapered steel conveyor rollers as has been required for servicing a curved conveyor section.
It has been determined that it is not essential for a tapered conveyor roller in a curved conveyor section to have a uniform taper from the outer end of the roller to the inner end in order to allow packages to move around a curve without changing orientation of the packages with respect to the roller conveyor. Thus in accordance with a preferred embodiment of the invention, an elongated rigid cylindrical base tube, such as a conventional steel tube having a uniform outer diameter, is supported for free rotation by a corresponding bearing and axle unit within each end portion of the base tube. A tubular sleeve of a plastics material, such as polypropylene having a slightly resilient outer surface, has an inner cylindrical surface which is press-fitted onto an end portion of the base tube. The plastic sleeve has a tapered outer surface and extends less than fifty percent of the length of the base tube and preferably, approximately one third the length of the base tube. The tapered sleeve has its largest diameter end positioned adjacent the outer end of the base tube, and the inner end of the tapered sleeve has an outer diameter only slightly greater than the outer diameter of the base tube.
Other features and advantages of the invention will be apparent from the following description, the accompanying drawing and the appended claims.